Libpsl is a C library which provides functions to check domains against the Mozilla Public Suffix List. It is useful for cookie domain verification, certificate domain verification, highlighting parts of a domain name, and more. Every Web client handling cookies (e.g. browsers) should use the PSL data to secure privacy.

cso is an easy to use C module that serializes objects into a simple binary format. It can be used to store data or to send it over a network. It supports either an object of type struct (CSO_DICT) or array (CSO_ARRAY) which contains elements of type integer of different sizes, double, binary, string, struct, or array.

s6-dns is a small, efficient, complete, and IPv6-ready DNS client library, with synchronous as well as asynchronous APIs. It is designed to replace libresolv in projects that need to perform DNS resolution. It also comes with small command-line utilities to make common and not so common DNS queries.

cmocka is a unit testing framework for C with mock objects. There are a variety of C unit testing frameworks available supporting different platforms and compilers. Some development requires a lot of different compilers and older versions, which makes it difficult to use unit testing frameworks. The idea of CMocka is that a test application only requires the standard C library and CMocka itself to minimize the conflicts with standard C library headers, especially on a lot of different platforms.

ext-Dns is a core library, an extensible forward DNS server, and some additional tools designed to create DNS server solutions which are able to do any additional operation at the resolution level (running commands, rewritting replies, gathering stats, and so on), without any limit. It provides a ready-to-use solution in case you want to build a DNS server which takes additional actions at the resolution level in an easy way. That is, its design is focused on allowing people to implement whatever they like when a request is received, freeing them from most of the details which involves handling DNS protocol.

fpgatools is a toolchain for programming flexible programmable gate arrays (FPGAs). The only supported chip at this time is the xc6slx9, a cheap (circa $10 U.S.) but powerful 45nm-generation chip with about 2400 LUTs, block ram, and multiply-accumulate devices. The principles of fpgatools are to reach the maximum physical performance of the chip, to provide fast development cycles, to be an independent toolchain which only depends on other Free Software, and to be a lightweight C implementation without a GUI.

EXIP provides a C library for the parsing and serialization of Efficient XML Interchange (EXI) format streams. The focus is portability and efficiency for embedded systems development. The project was started at the EISLAB research group in the Department of Computer Science, Electrical and Space Engineering, Luleå University of Technology, and is part of research efforts to bring resource-constrained embedded devices, such as wireless sensor nodes, closer to the enterprise business processes taking place in processing, manufacturing, and communication industries.

STALLioN is a cross-platform C/C++ library for creating coherent CLI/Terminal programs on multiple platforms with one codebase. It aims to provide a consistent development API across multiple platforms so that
separate code does not have to be created for each (often very different) terminal interface.